Showing papers by "Chung Yuan Christian University published in 1997"

Nuclear incompressibility and density dependent NN interactions in the folding model for nucleus-nucleus potentials

Abstract: A generalized version of density dependence has been introduced into the M3Y effective nucleon-nucleon $(\mathrm{NN})$ interaction that was based on the $G$-matrix elements of the Paris $\mathrm{NN}$ potential. The density dependent parameters have been chosen to reproduce the saturation binding energy and density of normal nuclear matter within a Hartree-Fock scheme, but with various values for the corresponding nuclear incompressibility $K$ ranging from 176 to 270 MeV. We use these new density dependent interactions in the folding model to calculate the real parts of $\ensuremath{\alpha}$-nucleus and nucleus-nucleus optical potentials for those systems where strongly refractive scattering patterns have been observed. These provide some information on the potentials at short distances, where there is a strong overlap of the projectile and target density distributions, and hence where the density dependence of the interaction plays an important role. We try to infer, from careful optical model (OM) analyses, the sensitivity of the scattering data to different $K$ values. Results obtained for elastic $\ensuremath{\alpha}$ scattering on targets ranging from ${}^{12}$C to ${}^{208}$Pb allow us to determine unambiguously that the $K$ value favored in this approach is within the range of 240 to 270 MeV. Similar OM analyses have also been done on measurements of the elastic scattering of ${}^{12}$C+${}^{12}$C, ${}^{16}$O+${}^{12}$C, and ${}^{16}$O+${}^{16}$O at incident energies up to 94 MeV/nucleon. These data were found to be much less sensitive over such a narrow range of $K$ values. This lack of sensitivity is due mainly to the smaller maximum overlap density which occurs for these systems, compared to that which is formed in an $\ensuremath{\alpha}$-nucleus collision. This makes the effects of density dependence less substantial. Another reason is that a small difference between two folded heavy ion potentials can often be compensated for, in part, by a small overall renormalization of one of them. This renormalization is often allowed in optical model analyses, and interpreted, for example, as accounting for a contribution from a higher-order dynamic polarization potential. In an attempt to avoid this ambiguity, some OM analyses of the extensive and accurate data for ${}^{16}$O+${}^{16}$O scattering were done using the unrenormalized folded potentials, together with the explicit addition of a correction term, expressed in terms of cubic splines. This correction term can be interpreted as representing a contribution to the real potential from the dynamic polarization potential. The results of such a ``folding+spline'' analysis suggest a tendency to favor the same $K$ value range that was found in the OM analyses of $\ensuremath{\alpha}$-nucleus scattering.

Developing a new transformer fault diagnosis system through evolutionary fuzzy logic

Abstract: To improve the diagnosis accuracy of the conventional dissolved gas analysis (DGA) approaches, this paper proposes an evolutionary programming (EP) based fuzzy system development technique to identify the incipient faults of the power transformers. Using the IEC/IEEE DGA criteria as references, a preliminary framework of the fuzzy diagnosis system is first built. Based on previous dissolved gas test records and their actual fault types, the proposed EP-based development technique is then employed to automatically modify the fuzzy if-then rules and simultaneously adjust the corresponding membership functions. In comparison to results of the conventional DGA and the artificial neural networks (ANN) classification methods, the proposed method has been verified to possess superior performance both in developing the diagnosis system and in identifying the practical transformer fault cases.

Real-time IP position controller design with torque feedforward control for PM synchronous motor

Abstract: A digital signal processor (DSP)-based permanent magnet (PM) synchronous motor (SM) drive with a proposed recursive least-square (RLS) estimator and real-time integral-proportional (IP) position controller is introduced in this study. First, the rotor inertia constant, the damping constant, and the disturbed load torque of the synchronous motor are estimated by the proposed RLS estimator, which is composed of an RLS estimator and a torque observer. Next, the IP position controller is real-time designed according to the estimated rotor parameters, to match the time-domain command tracking specifications. Then, the observed disturbance torque is fed forward, to increase the robustness of the synchronous motor drive.

Bi-objective power dispatch using fuzzy satisfaction-maximizing decision approach

Abstract: A fuzzy satisfaction-maximizing decision approach is presented to solve the bi-objective power dispatch problem regarding both minimum fuel cost and minimum environmental impact of NO/sub x/ emission. Based on the fuzzy utility functions of system operators and a fuzzy satisfaction-maximizing scheme, a set of noninferior solutions are obtained. For each noninferior solution achieved, the associated marginal rate of substitution (MRS) is then calculated to help the operators more rationally determine the weight factors of the objectives considered and hence the final best compromise solution. Numerical results of the IEEE 30-bus 6-generator test systems are presented to demonstrate the proposed fuzzy satisfaction-maximizing decision approach.

Multifunction biquadratic filters using current conveyors

Abstract: Some novel multifunction biquadratic filters with voltage gain, each of which employs four current conveyors, two grounded capacitors, and three-five resistors, are presented. Each proposed circuit offers the following advantageous features: realization of different biquadratic filter signals from the same configuration, no requirements for component matching conditions, employment of only two grounded capacitors which are ideal for integration, orthogonal control of /spl omega//sub 0/ and Q and low sensitivities.

Generation of Hermite-Gaussian modes in fiber-coupled laser-diode end-pumped lasers

Abstract: A general model has been developed for the generation of Hermite-Gaussian modes in fiber-coupled laser-diode end-pumped lasers by off-axis pumping. Hermite-Gaussian modes can be used as an M/sup 2/ standard in the calibration process due to the fact that these modes have a definite M/sup 2/ factor. The present model predicts how the oscillation of Hermite-Gaussian modes is affected by the pump position, the pump size, and cavity mode size. A straightforward procedure have also been provided to design the optical coupling system for the lowest threshold in the generation of Hermite-Gaussian modes. All of the key parameters of the optimum pump condition are in terms of laser-diode beam quality and properties of the active medium. Experimental results have shown a fairly good agreement with the theoretical predictions.

A parallel genetic algorithm approach to solving the unit commitment problem: implementation on the transputer networks

Abstract: Through a constraint handling technique, this paper proposes a parallel genetic algorithm (GA) approach to solving the thermal unit commitment (UC) problem. The developed algorithm is implemented on an eight-processor transputer network, processors of which are arranged in master-slave and dual-direction ring structures, respectively. The proposed approach has been tested on a 38-unit thermal power system over a 24-hour period. Speed-up and efficiency for each topology with different number of processor are compared to those of the sequential GA approach. The proposed topology of dual-direction ring is shown to be well amenable to parallel implementation of the GA for the UC problem.

Densities of Aqueous Blended Amines

Abstract: The densities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA) + water, DEA + 2-amino-2-methyl-1-propanol (AMP) + water, and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) + water were measured from 30 °C to 80 °C. A Redlich−Kister equation of the excess volume was applied to represent the density. Based on the available density data for five ternary systems: MEA + MDEA + H2O, MEA + AMP + H2O, DEA + MDEA + H2O, DEA + AMP + H2O, and MEA + 2-PE + H2O, a generalized set of binary parameters were determined. The density calculations show quite satisfactory results. The overall average absolute percent deviation is about 0.04% for a total of 686 data points.

On cluster-wise fuzzy regression analysis

Abstract: Since Tanaka et al. (1982) proposed a study of linear regression analysis with a fuzzy model, fuzzy regression analysis has been widely studied and applied in a variety of substantive areas. Regression analysis in the case of heterogeneity of observations is commonly presented in practice. The authors' main goal is to apply fuzzy clustering techniques to fuzzy regression analysis. Fuzzy clustering is used to overcome the heterogeneous problem in the fuzzy regression model. They present the cluster-wise fuzzy regression analysis in two approaches: the two-stage weighted fuzzy regression and the one-stage generalized fuzzy regression. The two-stage procedure extends the results of Jajuga (1986) and Diamond (1988). The one-stage approach is created by embedding fuzzy clusterings into the fuzzy regression model fitting at each step of procedure. This kind of embedding in the one-stage procedure is more effective since the structure of regression line shape encountered in the data set is taken into account at each iteration of the algorithm. Numerical results give evidence that the one-stage procedure can be highly recommended in cluster-wise fuzzy regression analysis.

Fuzzy adaptive model-following position control for ultrasonic motor

Abstract: A fuzzy adaptive model following mechanism for the position control of a traveling-wave-type ultrasonic motor (USM) is described in this study. Since the dynamic characteristics of the USM are difficult to obtain and the motor parameters are time varying, fuzzy adaptive control is applied to design the position controller of the USM for high-performance applications. The driving circuit for the USM, which is composed of a high-frequency boost DC-DC chopper, a two-phase series-loaded resonant inverter and an inner speed loop, is built first. Next, the control algorithm for fuzzy adaptive control is discussed. Then, a simple linear position control loop is designed and augmented by the model-following error-driven fuzzy adaptive mechanism to reduce the influence of parameter variations. The effectiveness of the proposed controller is demonstrated by some experimental results.

Fabrication of ZnSe quantum dots under Volmer-Weber mode by metalorganic chemical vapor deposition

Abstract: The possibility of fabricating quantum dots under Volmer–Weber growth mode is investigated. Layers of ZnSe/ZnS were grown by metalorganic chemical vapor deposition on both Si and GaAs substrates. The images of surface morphology, taken by atomic force microscopy, showed that the layers were grown in three-dimensional islands. Blueshift was observed in the photoluminescence spectra up to room temperature for these samples. This blueshift was shown to originate from the ZnSe islands. The effect of ZnSe growth duration was investigated. It was found that the blueshift increased with shorter ZnSe growth durations, but this near band gap emission disappeared when the ZnSe growth duration was longer than 5 s. Effects of quantum confinement and strain were considered to resolve the origin of the blueshift. Our result suggests that carrier confinement plays a dominant role.

Measurement of polyethylene wear in cementless total hip arthroplasty

Abstract: We made a clinical study of polyethylene wear in 240 hips of 187 patients having primary total hip arthroplasties from 1989 to 1990, using uncemented Osteonics components, with a head size of 26 mm. We excluded cups with anteversion of over 20° and measured linear wear by a new method using a digitiser and special software of our design. Follow-up was from two to five years (mean 4.3). The mean age at operation was 50.3 years, with more men than women (1.4:1). The mean linear wear per year was 0.15 mm; this did not increase with the longevity of the prosthesis (p = 0.54). In 59 hips showing evidence of osteolysis, the mean linear wear rate was significantly higher at 0.23 mm/year (p Our new method of measurement is time-saving and reproducible. The results confirm the greater rate of linear wear of polyethylene in patients showing osteolysis and in those who are younger.

Intelligent decision support for diagnosis of incipient transformer faults using self-organizing polynomial networks

Abstract: To serve as an intelligent decision support for power transformer fault diagnosis, a new self-organizing polynomial networks (SOPNs) modeling technique is proposed and implemented in this paper. The technique heuristically formulates the modeling problem into a hierarchical architecture with several layers of functional nodes of simple low-order polynomials. The networks handle the numerical, complicated, and uncertain relationships of dissolved gas contents of the transformers to fault conditions. Verification of the proposed approach has been accomplished through a number of experiments using practical numerical diagnostic records of the transformers of Taiwan power (Taipower) systems. In comparison to the results obtained from the conventional dissolved gas analysis (DGA) and the artificial neural networks (ANNs) classification methods, the proposed method has been shown to possess far superior performances both in developing the diagnosis system and in identifying the practical transformer fault cases.

Viscosities of Aqueous Blended Amines

Abstract: The viscosities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA), DEA + 2-amino-2-methyl-1-propanol (AMP), and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) were measured from 30 °C to 80 °C. A Redlich−Kister equation for the viscosity deviation was applied to represent the viscosity. On the basis of the available viscosity data for five ternary systems, MEA + MDEA + H2O, MEA + AMP + H2O, DEA + MDEA + H2O, DEA + AMP + H2O, and MEA + 2-PE + H2O, a generalized set of binary parameters were determined. For the viscosity calculation of the systems tested, the overall average absolute percent deviation is about 1.0% for a total of 499 data points.

Raman spectroscopy study of ZnSe and Zn 0.84 Fe 0.16 Se at high pressures

Abstract: The ZnSe powder and ${\mathrm{Zn}}_{0.84}$${\mathrm{Fe}}_{0.16}$Se crystal were studied by Raman scattering spectroscopy at pressures up to 36.0 and 32.0 GPa, respectively. For ZnSe powder at 4.7 and 9.1 GPa, two phase transitions were observed. However, the resulted phases have not been identified yet. As the pressure was increased to 14.4 GPa, the LO phonon peak disappeared while the TO phonon peak was still visible until the metallization pressure, 17.0 GPa was reached. In addition, three unidentified Raman peaks were still observable above the metallization pressure. For ${\mathrm{Zn}}_{0.84}$${\mathrm{Fe}}_{0.16}$Se crystal, the structure transition from possible zinc blende to sodium chloride phase (${\mathrm{B}}_{1}$) was identified by the disappearance of Fe local mode and longitudinal optical (LO) phonon mode at 10.9 GPa. In addition, an unidentified phase transition at 4.7 GPa was observed. The TO phonon and the split TO phonons were still observable at a pressure above the phase transition pressure up to 32.0 GPa. The existence of Fe impurity in the ZnSe up to a concentration of 0.16 reduced the semiconductor-metal phase transition pressure to 10.9 GPa. According to the calculation of Gr\"uneisen parameters, ${\mathrm{Zn}}_{0.84}$${\mathrm{Fe}}_{0.16}$ Se was found to have a higher ionicity than ZnSe. Reasons for the observation of Raman peaks at a pressure above the metallization pressure are still unknown.

Missing monopole strength in 58 Ni and uncertainties in the analysis of α-particle scattering

Abstract: Analyses of recent measurements of the scattering of alpha particles by ${}^{58}$Ni at energies of 129 and 240 MeV have indicated that only about a third of the sum rule limit for isoscalar monopole transitions was found in the giant resonance region of excitation energies ${(E}_{x}$ from 10 to 30 MeV). Here we examine the theoretical aspects of these analyses of inelastic scattering, both in the optical potentials obtained from elastic data and in the models used to represent the inelastic transitions. In particular we introduce the folding model and compare the use of folded optical and transition potentials with those obtained by deforming phenomenological optical potentials. We also study the effects of dynamic corrections on the folding interaction when this is density dependent. Both aspects are shown to have significant effects. We use more extensive elastic data at 139 and 340 MeV to illustrate the need for a density dependence in the folding interaction, as well as a need for different shapes for the real and imaginary parts of the potentials. Although these various features are shown to have non-neglible effects on the theoretical cross sections for the excitations at small angles, none of them is sufficient to account for all the apparently missing strength. We estimate, based upon the most realistic folding models, that about 50% of the sum rule limit for monopole excitation was observed within the two components of the spectra centered at 17.42 and 20.76 MeV. The sharing between these two components depends upon the assumptions made about the distribution of the giant dipole strength which also results in angular distributions that peak at 0$\ifmmode^\circ\else\textdegree\fi{}$. Thus about one-half of the sum rule limit appears to have been observed, rather than the one-third originally inferred from these data using the deformed potential model. These conclusions are based, on the one hand, upon the spectral decomposition proposed for the results of the 240 MeV experiment and, on the other hand, upon assuming that the simple breathing mode form is adequate for the monopole transition densities. The results may be sensitive to deviations from either assumption. In a similar way we also infer that at least 55%, and perhaps as much as 70%, of the isoscalar quadrupole sum rule limit may be present in this giant resonance range of excitation energies in ${}^{58}$Ni.

Driving circuit for ultrasonic motor servo drive with variable-structure adaptive model-following control

Abstract: A novel driving circuit is proposed to provide two-phase balance voltage for the travelling-wave type ultrasonic motor (USM) Moreover, the variable-structure adaptive model-following control is applied for the position control of the USM First, the single-phase equivalent model of the USM is described Next, the novel driving circuit, which is a two-phase chopper–inverter combination, is designed Since the lumped dynamic model of the USM is difficult to obtain and the motor parameters are time varying, the variable-structure adaptive model-following control is applied to design the position controller of the USM to reduce the influence of parameter variations and external disturbances The effectiveness of the proposed controller is demonstrated by experimental results

The effect of position on autonomic nervous activity in late pregnancy

Abstract: We investigated the effect of three different recumbent positions on autonomic nervous activity in late pregnancy. Thirty pregnant and 24 nonpregnant aged-matched women were studied, and measures of heart rate variability in both time and frequency domains were compared using supine, right and left lateral decubitus positions. In the nonpregnant women, the normalised high-frequency power was greatest in the right lateral decubitus position. In the pregnant women, the normalised high-frequency power was lowest and the low/high-frequency power ratio was greatest in the supine position. Both the percentage decrease of normalised high-frequency power and the percentage increase of low/high-frequency power ratio in the supine and right lateral positions were greater than those in the left lateral position. For women in late pregnancy, the left lateral decubitus position may be beneficial because cardiac vagal activity is least suppressed and cardiac sympathetic activity is least enhanced. Aortocaval compression might be the mechanism underlying the change in cardiac autonomic nervous activity when supine and right lateral decubitus positions are assumed in late pregnancy.

Polymers of carbonic acid. XXIV. Photoreactive, nematic or cholesteric polycarbonates derived from hydroquinone‐4‐hydroxybenzoate 4,4′‐dihydroxychalcone and isosorbide

Abstract: Numerous polycarbonates were prepared by means of “diphosgene” in pyridine using hydroquinone 4-hydroxybenzoate (HQHB) as mesogenic diphenol. In addition to the homopolycarbonate, binary copolycarbonates of HQHB and 4,4′-dihydroxychalcone (DHC) with varying molar composition were prepared. A series of ternary copolycarbonates were obtained by incorporation of isosorbide. Furthermore, an alternating copolycarbonate of HQHB and isosorbide was synthesized. All polycarbonates were characterized by inherent viscosities, elemental analyses, IR-, 1H-NMR, and 13C NMR spectroscopy, by WAXS powder patterns DSC measurements, and optical microscopy with crossed polarizers. The homopolycarbonate of HQHB and most binary copolycarbonates were semicrystalline materials forming an enantiotropic nematic melt. Particularly noteworthy is the finding that the alternating copolycarbonate of HQHB and isosorbide forms a broad cholesteric phase despite the unfavorable stereochemistry of isosorbide. The ternary copolycarbonates containing isosorbide formed a cholesteric melt and a Grandjean texture upon shearing. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1611–1619, 1997

Preparation and properties of SBS-g-DMAEMA copolymer membrane by ultraviolet radiation.

Abstract: A styrene-butadiene-styrene triblock copolymer (SBS) membrane was prepared by solvent casting. Grafting of dimethyl amino ethyl methacrylate (DMAEMA) to this SBS membrane was subsequently conducted by ultraviolet radiation-induced graft copolymerization without degassing to obtain a SBS-g-DMAEMA copolymer membrane. The graft copolymer was characterized by infrared spectroscopy and scanning electron microscopy. The degree of grafting and the mechanical properties of SBS and SBS-g-DMAEMA were measured. Contact angle, water content, and protein absorption of fibrinogen and albumin experiments were also performed to evaluate the biocompatibility of SBS-g-DMAEMA graft copolymer membranes. It was found that the degree of grafting was related to the irradiation time, DMAEMA concentration, and temperature. The tensile strength of the SBS-g-DMAEMA membrane increased with an increase in the degree of grafting. By using Kaelble's equation and the contact angle data, the surface tension of SBS-g-DMAEMA was determined. It was found that with an increase in the degree of grafting, the surface tension and water content of SBS-g-DMAEMA membrane increased, whereas the contact angle decreased. The amount of absorption of albumin and fibrinogen decreased with an increase in amount of grafting. However, there was a minimum for the adsorption of proteins in the SBS-g-DMAEMA membrane.

A high-performance induction motor drive with on-line rotor time-constant estimation

Abstract: A high-performance induction motor (IM) speed drive with online adaptive rotor time-constant estimation and a proposed recursive least square (RLS) estimator is introduced in this paper. The estimation of the rotor time-constant is on the basis of the model reference adaptive system (MRAS) theory; and the rotor inertia constant, the damping constant and the disturbed load torque of the IM are estimated by the proposed RLS estimator, which is composed of an RLS estimator and a torque observer. Moreover, an integral proportional (IP) speed controller is designed online according to the estimated rotor parameters; and the observed disturbance torque is fed forward to increase the robustness of the induction motor speed drive.

Cohorts structures for fault-tolerant k entries to a critical section

Abstract: We propose a structure named Cohorts to solve the problem of the access control of multiple entries to a critical section. Our solution is formalized as forming quorums in a k-coterie. It is resilient to node failures and/or network partitioning, invokes constant expected message cost and has comparably high availability.